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Date: Tue, 15 Dec 2020 11:18:55 -0600
To: "php internals" <internals@lists.php.net>
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Subject: Re: [PHP-DEV] [RFC] Short-match
From: larry@garfieldtech.com ("Larry Garfield")

On Tue, Dec 15, 2020, at 3:00 AM, Nikita Popov wrote:
> On Mon, Dec 14, 2020 at 6:34 PM Larry Garfield <larry@garfieldtech.com>
> wrote:
> 
> > I present to Internals this tiny RFC to follow up on the match()
> > expression RFC from earlier in the year.  There was solidly positive
> > support for this shortcut previously but it was removed for simplicity at
> > the time, with the intent to bring it back later.  It's now later.
> >
> > https://wiki.php.net/rfc/short-match
> >
> > --
> >   Larry Garfield
> >   larry@garfieldtech.com
> >
> 
> Just like Sara, I'm not strongly opposed to this, but I'm also not sure
> this is worthwhile. Writing "match (true) {" instead of "match {" is not
> particularly tedious when compared to the size of the remaining structure.
> Writing "match (true) {" has the advantage of being more explicit about
> what this actually does, namely a "true ===" comparison. If it is omitted,
> a reasonable person might think that
> 
>     match {
>         preg_match(...) => ...
>     }
> 
> is going to do something sensible, like it would if placed inside an
> "if()". But it does not, as preg_match() returns 1, not true, and as such
> the match arm will never be taken. This is more obvious when the value that
> is being compared against is explicitly given.
> 
> Of course, with "match {" being a dedicated syntax, we could make it a
> TypeError to use a non-bool match arm...
> 
> Regards,
> Nikita

Hm.  preg_match() is the first example I've seen that makes me think the weak comparison may have value in this case.  I will have to consider that and discuss with Ilija a bit.  (Since match was his addition and relates to the ongoing enum work.)  I'd also have to figure out how best to handle that, too, since it's a deeper change.  Whee!

Several people have mentioned also short-circuiting switch the same way.  I am not opposed, and honestly don't feel too strongly about it either way.  On Twitter, someone suggested also short circuiting while (true) the same way; I don't know how useful that is, but I acknowledge the consistency argument.  I'm happy with whatever the consensus is on both points.

--Larry Garfield